"""Tests for OpenTelemetry telemetry initialization."""

import pytest
from unittest.mock import MagicMock, patch, ANY
from src.telemetry import TelemetryService, get_tracer


@pytest.fixture
def reset_telemetry():
    """Fixture to preserve and restore global telemetry state."""
    import src.telemetry
    original = src.telemetry._telemetry_service
    yield
    src.telemetry._telemetry_service = original


class TestTelemetryService:
    """Test suite for TelemetryService."""

    def test_telemetry_service_init_enabled(self) -> None:
        """Test TelemetryService initialization when enabled."""
        with patch.dict("os.environ", {"OTEL_ENABLED": "true"}):
            service = TelemetryService()
            assert service.enabled is True
            assert service.service_name == "mosaic-coordinator"

    def test_telemetry_service_init_disabled(self) -> None:
        """Test TelemetryService initialization when disabled."""
        with patch.dict("os.environ", {"OTEL_ENABLED": "false"}):
            service = TelemetryService()
            assert service.enabled is False

    def test_telemetry_service_custom_service_name(self) -> None:
        """Test TelemetryService with custom service name."""
        with patch.dict("os.environ", {"OTEL_SERVICE_NAME": "custom-service"}):
            service = TelemetryService()
            assert service.service_name == "custom-service"

    @patch("src.telemetry.TracerProvider")
    @patch("src.telemetry.Resource.create")
    @patch("src.telemetry.OTLPSpanExporter")
    def test_telemetry_service_initialize(
        self,
        mock_exporter: MagicMock,
        mock_resource_create: MagicMock,
        mock_provider: MagicMock,
    ) -> None:
        """Test TelemetryService initialization with SDK setup."""
        with patch.dict(
            "os.environ",
            {
                "OTEL_ENABLED": "true",
                "OTEL_SERVICE_NAME": "test-service",
                "OTEL_DEPLOYMENT_ENVIRONMENT": "test",
            },
        ):
            service = TelemetryService()
            service.initialize()

            # Verify Resource was created with correct attributes
            mock_resource_create.assert_called_once()
            call_kwargs = mock_resource_create.call_args[1]
            assert call_kwargs["attributes"]["service.name"] == "test-service"
            assert call_kwargs["attributes"]["service.version"] == "0.0.1"
            assert call_kwargs["attributes"]["deployment.environment"] == "test"

            # Verify exporter was created
            mock_exporter.assert_called_once()

            # Verify TracerProvider was created
            mock_provider.assert_called_once()

    def test_telemetry_service_get_tracer(self) -> None:
        """Test getting tracer instance."""
        with patch.dict("os.environ", {"OTEL_ENABLED": "false"}):
            service = TelemetryService()
            tracer = service.get_tracer()
            assert tracer is not None

    @patch("src.telemetry.TracerProvider")
    def test_telemetry_service_shutdown(self, mock_provider: MagicMock) -> None:
        """Test TelemetryService shutdown."""
        with patch.dict("os.environ", {"OTEL_ENABLED": "true"}):
            service = TelemetryService()
            service.provider = mock_provider.return_value
            service.shutdown()
            mock_provider.return_value.shutdown.assert_called_once()

    def test_telemetry_service_shutdown_when_disabled(self) -> None:
        """Test shutdown when telemetry is disabled."""
        with patch.dict("os.environ", {"OTEL_ENABLED": "false"}):
            service = TelemetryService()
            # Should not raise exception
            service.shutdown()

    def test_get_sampling_ratio_default(self) -> None:
        """Test default sampling ratio."""
        with patch.dict("os.environ", {}, clear=True):
            service = TelemetryService()
            ratio = service._get_sampling_ratio()
            assert ratio == 1.0

    def test_get_sampling_ratio_custom(self) -> None:
        """Test custom sampling ratio."""
        with patch.dict("os.environ", {"OTEL_TRACES_SAMPLER_ARG": "0.5"}):
            service = TelemetryService()
            ratio = service._get_sampling_ratio()
            assert ratio == 0.5

    def test_get_sampling_ratio_invalid(self) -> None:
        """Test invalid sampling ratio falls back to default."""
        with patch.dict("os.environ", {"OTEL_TRACES_SAMPLER_ARG": "invalid"}):
            service = TelemetryService()
            ratio = service._get_sampling_ratio()
            assert ratio == 1.0

    def test_get_sampling_ratio_out_of_range(self) -> None:
        """Test sampling ratio is clamped to valid range."""
        with patch.dict("os.environ", {"OTEL_TRACES_SAMPLER_ARG": "1.5"}):
            service = TelemetryService()
            ratio = service._get_sampling_ratio()
            assert ratio == 1.0

        with patch.dict("os.environ", {"OTEL_TRACES_SAMPLER_ARG": "-0.5"}):
            service = TelemetryService()
            ratio = service._get_sampling_ratio()
            assert ratio == 0.0

    def test_get_deployment_environment_default(self) -> None:
        """Test default deployment environment."""
        with patch.dict("os.environ", {}, clear=True):
            service = TelemetryService()
            env = service._get_deployment_environment()
            assert env == "development"

    def test_get_deployment_environment_custom(self) -> None:
        """Test custom deployment environment."""
        with patch.dict("os.environ", {"OTEL_DEPLOYMENT_ENVIRONMENT": "production"}):
            service = TelemetryService()
            env = service._get_deployment_environment()
            assert env == "production"

    def test_get_otlp_endpoint_default(self) -> None:
        """Test default OTLP endpoint."""
        with patch.dict("os.environ", {}, clear=True):
            service = TelemetryService()
            endpoint = service._get_otlp_endpoint()
            assert endpoint == "http://localhost:4318/v1/traces"

    def test_get_otlp_endpoint_custom(self) -> None:
        """Test custom OTLP endpoint."""
        with patch.dict(
            "os.environ", {"OTEL_EXPORTER_OTLP_ENDPOINT": "http://jaeger:4318/v1/traces"}
        ):
            service = TelemetryService()
            endpoint = service._get_otlp_endpoint()
            assert endpoint == "http://jaeger:4318/v1/traces"


class TestGetTracer:
    """Test suite for get_tracer helper function."""

    def test_get_tracer_returns_tracer(self) -> None:
        """Test that get_tracer returns a tracer instance."""
        tracer = get_tracer()
        assert tracer is not None

    @patch("src.telemetry.trace.get_tracer")
    @patch("src.telemetry.trace.set_tracer_provider")
    def test_get_tracer_uses_service_name(
        self, mock_set_provider: MagicMock, mock_get_tracer_func: MagicMock, reset_telemetry
    ) -> None:
        """Test that get_tracer uses the correct service name."""
        with patch.dict("os.environ", {"OTEL_SERVICE_NAME": "test-service", "OTEL_ENABLED": "true"}):
            # Reset global state
            import src.telemetry
            src.telemetry._telemetry_service = None

            get_tracer()
            mock_get_tracer_func.assert_called_with("test-service")